Primer assembly for artillery ammunition



April 15, 1952 N. K. TURNBULL PRIMER ASSEMBLY FOR ARTILLERY AMMUNITION Filed Feb. 16, 1948 2 Sl-IEETSSHEET l R L m L m w m R Nw Q 9 W T v 2. 3 km R 1 m g n gm a mv L v v K a f m w n 1 V alll lllllv Y 4 J w 1 IIIII'IIII IIY M NM R w 47/7 m 3 IHIH TTORRiEYS.

April '15, 1952 N. K. TURNBULL 2,592,623

PRIMER ASSEMBLY FOR ARTILLERY AMMUNITION Filed Feb. 16, 1948 2 SX-lEETSSFE-ET 2 ZNVENTOR. NORMAN K. TURNBULL.

TGRNEYS i 'atentecl Apr. 15, 1952 PRIMER ASSEMBLY FOR ARTILLERY AMMUNITION Norman K. Turnbull, Pitman, N. J.

Application February 16, 1948, Serial N 0. 8,707

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 O. G. 757) 3 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon. v My invention pertains to artillery ammunition and is specifically a new and improved means of causing almost instantaneous detonation of all the grains in the charge of projectile propelling powder. 7

One object of my invention is to reduce the amount of time generally required to completely ignite the projectile propelling powder.

7 Another object of my invention is to provide means for causing the concentrated release of energy of the projectile propelling powder.

' Yet another object of my invention is to provide means for increasing the explosive effect of the projectile propelling powder.

A further object is to provide means for causing better utilization of the available pressure generated by the burning of the projectile propelling powder.

A still further object is to provide means for increasing the range of the projectile.

An additional object is to provide means for magnifying .the striking or impact force of the projectile.

In practicing my invention, I attain the foregoing and other objects by providing a unique and superior artillery ammunition primer assembly to be used in place of the conventional type of primer assembly.

One preferred form of my invention is shown in the accompanying drawings wherein:

Fig. 1 is a View of a complete round of artillery ammunition containing my inventive primer assembly, parts of the cartridge case wall and propellent charge having been removed to expose some of the components of my novel device.

Fig. 2 is an end view of said round of ammunition as viewed from line 2-2 of Fig. 1.

Fig. 3 is an enlarged longitudinal sectionof my primer assembly taken along line 33 of Fig. 2.

Fig. 4 is a view similar to Fig. 3 except that it illustrates an alternate form of my invention wherein a plurality of plunger rods are utilized, each one being spaced between a pair of percussion caps.

In the discussion of my invention hereinafter, for convenience of reference to the drawings, it will be understood that the word rear refers to portions of components facing the closed base end of the illustrated cartridge case, whereas the term front refers to those portions of components facing the open mouth end of the cartridge case.

The 'above objects are accomplished by my superior primer assembly which consists essentially of two or more percussion caps spaced one from the other, and a plunger rod located between each pair of such caps and capable of detonating those caps in front of the rod upon being thrust axially forward into sharp contact therewith. For purposes of explanation it will be suflicient to limit the following discussion to a primer assembly using two percussion caps; however, it will be obvious that a plurality of caps and plungers may be employed without departing from the scope of this invention. The simplest form of my invention, wherein only two caps and one plunger rod are employed, is shown in Fig. 3; the use of a plurality of plunger rods is shown in Fig. 4.

In the example of Fig. 3, one cap is located at the base end of the cartridge case, the second is located in the front end of the primer tube axially aligned with, but at a distance from said basepositioned cap. Between the two is a novel plunger rod so restrained as to be immobile and inoperative during normal handling, but adapted to become mobile when the round is fired in a manner and for reasons explained below.

When the round of ammunition is fired, the gaseous pressure from ignition of the first or basepositioned percussion cap causes a break in the means restraining the plunger and further causes the plunger to spring rapidly toward the front end of the primer tube to detonate the second percussion cap. The individual flames which result from detonating the two (or more) percussion caps cause the almost instantaneous ignition of the projectile propelling charge en masse, thereby resulting in the spontaneous generation of a tremendous initial pressure Within the cartridge case. This pressure causes the projectile to be shot therefrom with greater velocity and impetus than has heretofore been attainable with a given amount of propellent and the conventional single, base-positioned percussion cap.

A more detailed impression of my invention will be gained from the following description of an actual model thereof, and reference to the accompanying drawings which illustrate same.

Fig. 1 shows a complete round of artillery ammunition employing my novel improvement. As there shown, the round consists of an annular cartridge case 6 of conventional design having base end I which is closed except for a relatively small central opening therethrough and an open primer assembly 9 which is pressed frictionally' tight into the base I of the cartridge case 6, and projects therefrom toward the mouth end 8 of said cartridge case in concentric relationship therewith (see Fig. 2)

Once my primer assembly 9 is positioned in the base 1 of cartridge case 6, the projectile propelling charge 10 and a retaining disc H are added within said case. added to the mouth end! of the cartridge case 3 and the rim of said mouth end is crimped into a suitable circumferential groove [3 provided therefor in the projectile.-

A longitudinal section through the cartridge case 6, my novel primer assembly 9, and the projectile propelling charge it is shown in Fig. 3. Here the assembly 9 is seen to consist of a base member l4 having a flanged portion IS, a body portion l3 and a threaded portion H.

The base member i4 bears a recess which accommodates'a firing plug 58 having a hammer portion 59 of reduced diameter and a firing protuberance 20, the several parts being mounted in a sleeve 2! internally shaped so as to prevent loss or removal of said firing plug l8. Located adjacent the firing plug in the base member I4 is the first percussion cap 22. The firing plug and the first percussion cap are'relatively so positioned that the firing protuberance rests lightly in contact with said percussion cap 22 L when the firing plug is in its most rearwardposition within the sleeve 2!. The firing plug 18, however, is free to slide in'its sleeve 2! forwardly toward the first percussion cap 22 under impact from a weapons conventional firing 'pin (not shown) when the ammunition round is fired.

Continuous with the front end of the recessin base member i4 containing the first percussion cap 22 is a primer vent hole 23 communicating with an axial holeof somewhatlarger diameter which is filled by the fiat end 24 of the plunger rod 25. This plunger rod preferably takes the form shown in Fig. 3, havinga' blind hole or cavity 26 leading inwardly from its rear or fiat end 24 into an otherwise solid member, and a conical point 2? at its front extremity.

Threadably attached to threaded section I! of the base member 14 is the primer tube 28 having perforations 29 arranged in staggered rows preferably equally spaced radially and longitudinally. The said perforations are preferably filledwith a readily frangible or combustible protective material 36 (such as a synthetic vinyl'resin). The primer tube may, if desired, be furnished with a conventional liner such as is indicated at 3i. This liner, likewise made of a readily frangible or combustible material such as kraft paper or suitable resin, serves in conjunction with material '3fi to prevent the charge of powder 4| in tube 28 from escaping through perforations 29, p articularly during assembly of the ammunition round;

At the front end of primer tube 28 its bore is completely filled by an end plug 32, having an axial l1ol-e3i at its forward end'continuous rear- A projectile I2 is then' 4 wardly with a recess 39 of much greater diam eter. Housed in recess 39 at its front end is the second percussion cap whose open or mouth end forwardly faces the axial hole 31. Also housed in recess 39, but at its rear end, is a retaining plug 36 having an axial opening 38 therethrough and so positioned that its front end contacts the rear or closed end of cap 35. A hole,

' shown filled by a shear pin 40, is provided in plug 35. passing transversely through the cylindrical walls as shown in Fig. 3.

In assembling my novel priming device, prior to installing the plunger rod 25 into tube 28, the rod is-placed with its conical end 21 into its illustrated'p'osition in opening 38, and shear pin 40 is passed'through the mating hole provided therefor in the rod and in plug 36. Percussion cap 35 is' placed in its proper position in plug 32 and then plug 36 (with the rod 25 joined thereto) is press-fitted into place within plug 32, following which these parts are fitted into the Fig, 3-position at the front end of the primer tube 28, the flat rearend 24 of rod 25 being located in its proper position at the same time. A circumferential V-shaped groove 33 is provided around the outside of plug 32 and, by staking the wall of tube 28 thereinto as indicated at 34, the parts contained in the front end of the primer tube are fixed against movement.

Finally, there isplaced in the frontend of tube 28 a container such as the cardboard cup 43 filled with an igniter powder charge 42'; This cup is prepared for use by filling it with powder 42, then placing thereon a ring-shape, relatively thickwalled cover 44=whose center'opening is covered over by a relatively thin paper or other frangible disc 45 (which may, for convenience, be glued to cover 44) Cover 44 together with disc 45 1serves to keep the ignite charge 42 in cup 43. The diameter of the central hole through cover is such that it provides a snug fit with the outer wall of tube 28, while the overall diameter of cover 44 is such that it provides a snug fit withinthe open end of cup 43..

The alternative form of my invention shown in Fig. 4 consists of a cartridge case having a perforated primer tube assembly similar 2 to that shown in Figs l and 3.. The modified assembly consists of a base member l4 having afianged portion I5, a body portion I6 and athreaded portion ll.

The base member I4 bears a recess which accommodates' a sleeve 2 IA that housesafirst per: cussioncap 22. Continuous with the front, end ofthe recess in base member I4 is a firstprimer vent hole 23 communicating with an axial hole of somewhat larger diameter which is filled by the fiat end 24Aof a first plunger rod 25A. This plunger rod hasa blind holeor cavity 26A'leading inwardly from its rear end 24A into'an' otherwise'solid member, and a conical pointZTA at its front extremity.

Threadably attached to base member I4 is a first section 28Aof the primer tube having-perforations 29A spaced radially and longitudinally. These perforations are filled with a readily combustible protective material 30. A conventional liner 3| of kraft paper is employed to prevent the pogvder charge 4'l from escaping from the primer A second primer tube section 28B is located forwardlyof the first section 28A, both sections being threadedlyjoin'ed as at 54 toan adapter 52 which hassubstantially the same internal" and external diametral dimensions as the primer tubes. Adapter 52 is provided with a recess 53 in which is accommodated a second percussion cap 50. Behind this cap is a cylindrical plug 56 having an axial opening 51 therethrough. In front of the cap is a second primer vent hole 51 communicating with an axial hole. of somewhat larger diameter which is filled by the fiat end 24B of a second plunger rod 25B. This plunger rod also has a blind hole or cavity 2613 leading inwardly from its rear end 24B into an otherwise solid member, and a conical point 213 at its forwardmost extremity.

The remainder of the assembly is identical with the form of my invention shown in Fig. 3. At the front end of primer tube 283 its bore is completely filled by an end plug 32 having an axial hole 31 at its forward end continuous rearwardly with a recess 3-9 of much greater diameter. Housed in recess 39 is a third percussion cap 35 whose open or mouth end forwardly faces the axial hole 31. Also housed in recess 39, but at its rear end, is a retaining plug 36 having an axial opening 38 therethrough and so positioned that its front end contacts the rear or closed end of cap 35. The conical rod end 273 is lightly pressed-fitted into opening 38 and thus retained there until impelled forwardly by the force of explosive gases upon the rods rear end. In a similar fashion, conical end 21A of first plunger rod 25A is press-fitted into axial opening 51 in plug 56.

The assembly of the Fig. 4 modification follows very closely the plan set forth earlier for assembling the Fig. '3 device. Circumferential V- shaped groove 33A and the staking of primer tube section 2813 as shown at 34A are comparable to similar provisions shown in the preferred form of Fig. 3.

The operation of the Fig. 4 modification should by now be apparent. A blow struck on cap 22 detonates it and forces rod 25A to move forwardly to detonate cap 50. This in turn, almost simultaneously, causes rod 253 to move forward and set off cap 35. If more rods and more caps were thus assembled, a whole series of these successive detonations would occur, and the powder charges l! along the primer tube section would simultaneously be ignited and spark the main charge outside the primer tube proper.

From the foregoing the operation of my invention should be obvious to those generally skilled in the art. The complete round embodying my primer assembly is loaded into a suitable firearm (not shown) and the usual preparation is made for firing. When the trigger (not shown) of said firearm (not shown) is released, a firing pin (not shown) springs rapidly forward and strikes the firing plug l8 causing it to move toward the first percussion cap 22. The firing protuberance 20 strikes against and thereby detonates the first percussion cap 22.

Gas generated by detonation of the first percussion cap or primer rushes with great speed against the flat end 24 and into the blind hole 2% of the plunger 25. The gas pressure exerts a forwardly directed force on the plunger rod sufilcient to fracture the shear pin 40 and cause the plunger to shoot from its Fig. 3 at rest position forwardly through the axial opening 38 so that the plungers conical point 2'! strikes and detonates the second percussion cap 35. The blind hole 26 is not absolutely essential to the just described operation, but it greatly aids in concentrating the gas pressure and thereby exerts a greater 6 force upon the plunger rod than could be ob tained without such aid.

Coincident with the detonation of second percussion cap 3-5 flame rushes from the first cap 22 through the hole 23 (which is no longer closed off by part 24 of rod 25) to ignite the igniter charge 4 I. At the opposite or front end of primer tube 28 flame from the second percussion cap 35 rushes into the axial opening 31 consumes the disc 45 and ignites the igniter charge 42 which in turn ignitesthe forwardly situated grains of the propellent charge H3. The liner 3|, the protective material 30, and the cup 43 are likewise summarily consumed by explosion of the igniter charge 42 and the igniter charge 4| The projectile propelling charge [0 is ignited by the combined and spontaneous action of the flames from the first and second percussion caps 22, 33, the primer charge M and the igniter charge 42. The rearwardly positioned grains of the propelling charge are ignited by burning of igniter charge 4| which is set off by percussion cap 22, and the forwardly positioned propellent grains are ignited by the explosions of igniter charge 42 set off by percussion cap 35.

The almost instantaneous and complete ignition of the projectile propelling charge In en masse results in the generation of a tremendous initial pressure which causes the projectile to be shot with greater velocity and greater impetus. As will be obvious, this is far superior to conventional means for igniting the propellent charge which generally rely on igniting the charge by a rearwardly disposed primer only, the flame therefrom successively igniting portions of the propellant as the flame travels axially forward and radially outward through perforations in the primer tube. The en masse ignition of the propellant provided for by my improvement makes possible the better utilization of available pressure generated by burning of the propellant, increases the range of the projectile and magnifies the projectiles striking or impact force.

From the foregoing description and accompanying illustrations it will be apparent that I have developed a novel artillery ammunition priming device which reduces the amount of time generally required to completely ignite the projectile propelling charge; that I have provided means for causing the concentrated release of energy of the projectile propelling powder; that I have provided means for increasing the explosive effect of the projectile propellant; that I have provided means for causingbetter utilization of the available pressure generated by the burning of the projectile propelling powder; that I have provided means for increasing the range of the projectile; and that I have provided means for magnifying the striking or impact force of the projectile.

It will be obvious especially to those familiar with this art, that my herein disclosed invention may be modified in numerous ways without materially departing from the scope or spirit of the invention, and it is not intended unnecessarily to limit myself to the specific form herein described and illustrated.

I claim: I

1. In an ammunition round, a hollow cartridge case having at its rear end a base which is closed except for a relatively small opening therethrough and at its front end an open mouth, propellent powder substantially filling said cartridge case, a projectile fitted within the mouth of said case, a primer tube having spaced perforations in its wall and axially extending from: the base of said case forwardly thereinto, a liner of combuse tible material covering the -tube perforations, a charge of explosive powder in. saidtube, a container of igniter powder attached adjacent the free end of said tube, a first percussion cap as-. sembly. mounted in said tube near the case base and having a vent hole through whichexplosive gases-from said cap'are forwardly expelled, a second percussion cap mounted in and near said tubes free end, and a plunger rod mounted intermediate'said caps having a tapered forward end'and a rear end bearing a blind axial cavity which is disposed so as to be in direct communication with the vent hole in said first cap assembly in order that the explosive gases issuing therefromwill collect in the cavity and thus maximize the force exerted on said plunger rod whereby a sharp detonating'blow delivered to saidfirst cap will' develop a fire which ignites the explosive powder and the rearwardportions of the propellent powder and also will release a gas which drives the plunger rod forwardly to detonate said second cap so that the igniter powder andthe forward portions of the propellent powder are ignited almost simultaneously with the ignition caused by the first cap.

2. Inan artillery cartridge case containing propellent powder, means for firing said propellent powder comprising, a plurality of longitudinally aligned percussion 'caps spaced from each other with the rearmost one located in the case base, a plurality of plunger rods each of which individually is mounted for longitudinal movement between a successive pair of caps and each of which has at its rear end a blind axial cavity which is disposed so as to'be in direct communication with the cap immediately behind it in order that the explosive gases issuing from the neighboring cap will collect in the cavity of the adjacent plunger rod and thus maximize the longitudinal force exerted on the rod, and a powder charge associated with said caps in easy communication with said propellent powder, the various components being- 32 so related that. detonation" of the percussion cap inthecase base releases fir'e which ignites the powder charge and also-releases gas which'drives an adjacent one of ath'e: plunger rods forwardly against the next'fcapin' line, this action successivelybeing transmitted throughout the line of caps soas to set fire tothe easily communicable propellent powder ina number of places almost simultaneously and thereby substantially to ignitethatpowde'r' en masse.

3; In an artillery cartridge: case containing propellent powder; the means for firing :said propellent powder as described in claimi2, additionally including means normally operative to prevent the plunger rods from accidentally strikingithe percussionicaps but. capable of being ren-" dered inoperative for this purpose upon the rods being driven longitudinally-forward by gases developed from detonation of the'corresponding cap situated to the rear of each rod.

NORMAN K. TURNBULL.

REFERENCES CITED The following references are of record in the file of this. patent:

UNITED STATES PATENTS Number Name Date 643,974 Parker Feb. 20, 1900 2,382,118 Weinberger Aug; 14, 1945 2,446,187 Meister Aug, 3,1948

FOREIGN PATENTS Number Country Date 35,128 Germany Apr. 3, 1886 194,343 Germany d. Jan. 18, 1908 OTHER REFERENCES Publication and drawing relating to an exhibition representing results of the research activities .of the Carnegie Institution of Washington; D. C., held December 14-16, 1935-. Publication classified in 102-138 as an uxr. Pages 43 and 44, one sheet drawing. 

